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Photoactive Fe(III) complexes of α-hydroxy acid containing ligands

INGLE, SHAKTISINGH K
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1144708291

Abstract Details

2006, MS, University of Cincinnati, Arts and Sciences : Chemistry.
The α–hydroxy carboxylic acid group in marine siderophores is photoactive when bound to Fe(III). This photochemical reaction in natural sunlight reduces Fe(III) to Fe(II) making it more available for biological uptake. Iron complexes of α–hydroxy acid containing ligands inspired by these siderophores were synthesized and their photochemical reaction was studied. The ligands were synthesized starting from (S)-(-)-4-amino-2-hydroxy-butyric acid in 5 steps. First three steps include acid group protection in (S)-(-)-4-amino-2-hydroxy butyric acid with methyl ester. The alkylation on amine was carried out using ethyl bromoacetate and chloroacetohydroxamic acid to get ester forms of carboxylate(4A) and hydroxamate(4B) ligands. The final acid form of ligands (5A and 5B) was obtained after hydrolysis of the ester groups. Both these complexes, when mixed with bathophenonthroline disulfonate (BPDS), Fe(II) specific chelating agent, showed Fe(II) produced under different light conditions. Fe(II)(BPDS)3 band has characteristic band at 533 nm. This band was monitored by UV-Visible spectroscopy over time for the production of Fe(II). About 70 % of iron was trapped as Fe(II) in both the Fe(III)-carboxylate (Fe(III)(5A))and Fe(III)-hydroxamate (Fe(III)(5B)) complexes. The chiral center at the α–carbon of α–hydroxy acid group gives rise to well resolved circular dichroism (CD) bands in Fe(III)-carboxylate complex. The spectrum recorded after the irradiation of the complex solution in water showed that there was no more CD band present. This loss of CD band as a result of loss of chiral center in the ligand indicates oxidation of the α–hydroxy acid group as a result of photochemistry. However, under anaerobic conditions, the CD spectrum did not show complete loss of chirality. This incomplete photolysis of ligand showed that the ratio of metal:ligand for complete photochemical reaction is higher than 1:1. In summary, Fe(III)(5A) and Fe(III)(5B) complexes were found to undergo photochemical reaction resulting in iron reduction and ligand oxidation. These complexes may potentially have applications in light-triggered metal delivery agents, light-activated coatings, and oxidation state specific iron sensors.
Dr. Michael Baldwin (Advisor)
81 p.
Chemistry, Inorganic

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Citations

  • INGLE, S. K. (2006). Photoactive Fe(III) complexes of α-hydroxy acid containing ligands [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1144708291

    APA Style (7th edition)

  • INGLE, SHAKTISINGH. Photoactive Fe(III) complexes of α-hydroxy acid containing ligands. 2006. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1144708291.

    MLA Style (8th edition)

  • INGLE, SHAKTISINGH. "Photoactive Fe(III) complexes of α-hydroxy acid containing ligands." Master's thesis, University of Cincinnati, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1144708291

    Chicago Manual of Style (17th edition)

ucin1144708291
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© 2006, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
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